UCA-based orbital angular momentum radio beam generation and reception under different array configurations

The Orbital-Angular-Momentum (OAM)-carrying radio waves may provide extra rotational degree of freedom, which may potentially increase channel capacity and spectrum efficiency for future wireless communications. It has been demonstrated that circular antenna array could radiate OAM-carrying radio beam by feeding each element with certain phase offset. In this paper, by proper analyses and extensive simulations on the spatial amplitude and phase characteristics of the radiated electromagnetic field under three different array configurations, i.e., radial array, tangential array, and uniform circular array (UCA), respectively. We found that among the above settings UCA is the best way to generate the desired OAM-carrying beam with linear excitation. We then use multiple concentric antenna rings with elements of half-wave dipoles to generate and demultiplex multiple OAM states, and both spectral analyses and simulations verified the feasibility.